欧州の長期的な強さと,プレート成形プロセスへの影響
1Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3PR, UK. martap@earth.ox.ac.uk
Nature
|July 22, 2005
まとめ
大陸のクラトンは,より若い地質学的な地域よりも強い. この研究では,石層の強度 (有効弾性厚さ,Te) を測定する方法を調和させ,古いクレートンは若い地域よりもTeが著しく高いことを明らかにしました.
科学分野:
- 地質物理学 地質物理学とは地質物理学です.
- テクトニクス (地質学) とは
- 地球科学 地球科学 地球科学
背景:
- 大陸の変形は若い地質学的な地方に集中し,クラトンはより強いことを示唆しています.
- 構造的変形の重要な要因であるアルカイア期とファネロゾイア期の石層の相対的な強さは依然として議論されている.
- 効果的な弾性厚さ (Te) は石層の強さのプロキシですが,空間的な変動と測定の不一致があります.
研究 の 目的:
- 2つの異なる方法の一貫した配列を使用して,ヨーロッパ全体で有効な弾性厚さ (Te) の変動性を推定する.
- "ブーゲーの一貫性"と"空気の入口"の方法から得られた異なるTeの推定値を,特にクラトニックの領域で調和させる.
- 岩層の強度 (Te) と地質学的年齢との関係を調査する.
主な方法:
- ヨーロッパで有効な弾性厚さ (Te) を推定するために"ブーゲール一貫性"と"空気の入口"の方法を適用しました.
- 結果の直接比較を可能にするため,両方の方法の一貫した構想を保証しました.
- 推定Te値は地質年代と地域地質学と相関しています.
主要な成果:
- 一貫して策定された場合,両方の方法は,地質学的な州と相関する比較可能なTe値を生成します.
- 古い石層 (≥ 1.5 Gyr) は,若い石層 (平均 Te < 30 km) に比べて,著しく高い強度 (平均 Te > 60 km) を表しています.
- 以前の研究,特にクラトンにおける方法の差異は,一貫した構想によって軽減されます.
結論:
- リトスフィアの強さは地質学的な年齢に強く依存しており,古代のクラトンは若い州よりもかなり強い.
- 観測された強さの差は,厚さ,地熱的梯度,および組成を含む石層プレート構造の進化的変化に起因する.
- 地球の歴史を通じてマントルの温度と揮発性物質の含有量の低下は,これらの構造的変化に影響を与え,その結果,石層の強さの変動を引き起こした可能性があります.
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